A spring configuration of a floating-caliper disc brake is known from DE 33 36 302 A1 where the floating caliper is a fist-type caliper without frame. A retaining spring bent in one piece from wire is riveted to the back side of the axially outer brake pad and is moreover secured against twisting in the plane of the brake disc. Two free spring arms support themselves axially on the outside of the fist leg and secure with bias the brake pad axially relative to the fist leg. One sole spring arm designed as parallel spring extends tangentially towards one side and supports itself on a carrier arm of the brake carrier in order to secure with bias the brake pad radially relative to the brake carrier. The radial securing with bias of the fist-type caliper relative to the brake carrier is done indirectly in that the outer brake pad is coupled to the fist leg of the fist-type caliper by means of a catch.
Regardless of the fact that such a spring configuration cannot be used with a floating-caliper disc brake with a fist-and-frame-type caliper there are further disadvantages. The fact that there is provided but one sole spring arm for the radial securing with bias involves the introduction of a torque into the brake pad in the plane of the brake disc whereby the brake pad located on the side opposite the sole spring arm tends to lift off from the carrier arm of the brake carrier. Efficient control of clattering noises will thus not be achievable. Moreover, the retaining spring is undetachably connected to the brake pad and will therefore have to be exchanged together with the worn brake pad.
Another spring configuration of a floating-caliper disc brake with a fist-type caliper without frame is known from DE 43 31 633 A1. A retaining spring bent in one piece from wire is detachably connected with the axially outer brake pad and secures with bias the brake pad radially relative to the brake carrier by means of two lateral spring arms. The fist-type caliper is also indirectly secured with bias relative to the brake carrier thanks to the fact that the brake pad is coupled with the fist leg of the fist-type caliper via two axially projecting catches. Projecting on the back side of the carrier plate of the brake pad are two notched nails disposed at a certain distance on top of each other which receive a lozenged looping formed in the central area of the retaining spring. For assembly and disassembly, the retaining spring must be twisted by 90 degrees in the plane of the brake disc so that the retaining spring can be moved over the heads of the notched nails thanks to the bigger distance between the respective corners of the lozenged looping of the retaining spring. Regardless of the fact that it does not become evident from DE 43 31 633 A1 whether or not the spring configuration also secures with bias the outer brake pad axially relative to the outer floating-caliper leg, this spring configuration cannot be used with a type of floating-caliper disc brakes equipped with a fist-and-frame-type caliper.
It is an object of this invention to provide a suitable spring configuration for a floating-caliper disc brake equipped with a fist-and-frame-type caliper.
The spring configuration of the present invention provides a retaining spring which is bent in one piece from wire and which includes a central section, detachably connected with the axially outer brake pad, and two spring arms essentially projecting from the central section in opposite tangential directions and which both secure with bias the fist-and-frame-type caliper radially relative to the brake carrier and secure with bias the axially outer brake pad axially relative to the inside of the outer fist-and-frame-type-caliper leg. Such a spring configuration is particularly suited for a floating-caliper disc brake with a fist-and-frame-type caliper
In a preferred embodiment, a spring configuration is disclosed which is beneficial for a floating-caliper disc brake with a fist-and-frame-type caliper which, in the central area of its axially outer fist-and-frame-type-caliper leg, comprises a leg window and which, on both sides of this leg window, comprises apertures for an axial carrier arm each of the brake carrier stationarily connected with the chassis and which features a symmetrical design, particularly so with regard to a central plane extending transversely to the brake disc. In this embodiment the central section of the retaining spring is provided to be arranged essentially within the leg window of the outer fist-and-frame-type-caliper leg and the two spring arms of the retaining spring are provided to be disposed essentially on the outside of the outer fist-and-frame-type-caliper leg and each to reach with their outer end sections axially through the apertures provided in the fist-and-frame-type caliper for the carrier arms of the brake carrier and moreover to support themselves slidingly with radial bias on the undersides of the carrier arms of the brake carrier.
An advantageous embodiment of the spring configuration is disclosed having an easily manufactureable detachable connection of the retaining spring with the outer brake pad and the latter's axial pull support against the inside of the fist-and-frame-type-caliper leg. To this end, the central section of the retaining spring comprises a central part which is bent like a hairpin and the legs of which reach behind an enlarged, preferably axially outwards tapering head of a pin disposed on the outer brake pad and axially projecting therefrom into the leg window. Moreover, via corresponding connecting sections, the central part of the retaining spring is connected under axial tensile stress with a spring arm each of the retaining spring which axially support themselves on the outer fist-and-frame-type-caliper leg. To produce this detachable connection between the retaining spring and the brake pad, the central part of the retaining spring which is bent like a hairpin will just be slid with its open side in the radial direction onto the pin and engage the head from behind. An axially tapering shape of the head also enables another kind of assembly, with the hairpin-shaped central part axially being snapped onto the pin of the brake pad and with the legs of this hairpin-shaped central part temporarily being resiliently straddled apart.
An embodiment of the spring configuration is disclosed which provides the two legs of the hairpin-shaped central part each to pass over into a second leg bent like a hairpin into the opposite direction which passes over into an outer spring arm of the retaining spring by way of an essentially axially extending portion. This design enhances the elasticity of the central section of the retaining spring both in the tangential and axial directions, thereby facilitating both assembly and disassembly of the retaining spring.
Another variant of the spring configuration is disclosed which aims at a further facilitation with regard to the assembly of the retaining spring and permits a simpler configuration of the retaining spring. Here, the central section of the retaining spring is provided to have a tangentially extending central part whence, on both sides, a leg extends against the radial direction, with these two legs again each passing over into the spring arms of the retaining spring via an essentially axially extending portion. The two axial portions are designed so as to support themselves each with a section, preferably punctually, on the bottom side of the leg window and thus are connected with the spring arms of the retaining spring so that there is a tilting moment in the central section of the retaining spring which will pull the central part of the retaining spring outwards.
Also disclosed is an embodiment which provides the tangential central part of the central section of the retaining spring to be hung up behind a metal tongue which is fastened to the back side of the outer brake pad and is open preferably downwards, opening with a step-like expanded section. When mounting the retaining spring, in this case, the central tangential part of the retaining spring is inserted from below and disposed behind the metal tongue, with the retaining spring being swiveled around its longitudinal axis so that it supports itself with the respective sections on the bottom side of the leg window while simultaneously its tangential central part is moved in the radial direction on the back side of the metal tongue. The step-like expanded section of the metal tongue facilitates the assembly of the retaining spring in that it provides the retaining spring with a temporary support in a suitable intermediate position during its assembly.
An additional embodiment enables the retaining spring to be given a shape as simple as possible while its function is fully ensured although the predetermined geometrical conditions are relatively complicated due to the special type of a floating caliper. It is provided that the two spring arms of the retaining spring each support themselves in their central area against the radial direction and with their inner spring leg, which points to the central section, in the radial direction on an axial projection or recess provided on the frame of the fist-and-frame-type caliper.
Again, there are two beneficial variants in this respect. One embodiment provides that the central areas of the two spring arms of the retaining spring each are designed as spiral looping and each are supported on a cylindrical axially projecting pin disposed on the frame of the fist-and-frame-type caliper and that the inner spring legs of the two spring arms of the retaining spring support themselves on the upper side of an axially open groove-like recess in the frame of the fist-and-frame-type caliper. This design ensures a very reliable fitting of the retaining spring. On the other hand, it requires the existence of axially projecting pins on the frame of the fist-and-frame-type caliper which may be a disadvantage if the constructional space available in the axial direction is but of minimum size.
In a preferred design the central areas of the two spring arms of the retaining spring are designed as vertices pointing against the radial direction and being the vertices of two spring legs extending at an obtuse angle in respect of each other which support themselves on the bottom side, i.e. on the side pointing in the radial direction, of an axially open groove-like recess of the frame of the fist-and-frame-type caliper. Simultaneously, the respective inner spring legs of the two spring arms each support themselves on the upper side of this groove-like recess, i.e. on the side of the groove-like recess which points against the radial direction. The particular advantage of this design is that it needs less constructional space in the axial direction of the disc brake and that, moreover, the shape of the retaining spring is less complicated and thus easier to manufacture.
To ensure a reliable locking of the retaining spring in the axial direction of the disc brake in all situations an embodiment is disclosed wherein the free ends of the retaining spring which adjoin the outer end sections of the spring arms which reach through the apertures of the fist-type frame are bent so that they engage the inside of the frame of the fist-and-frame-type caliper from behind, thus locking the retaining spring axially on the fist-and-frame-type caliper.